Process for the extraction of material from multi-phase systems

ABSTRACT

A method for extracting and separating extractive components from fluids is provided. A first fluid and an extraction fluid are added to a vessel, thereby creating a two-phase two-layer system, wherein the first fluid and the extraction fluid are discrete and the two-phase system has a first fluid/extraction fluid interface. The two-phase system is then agitated, wherein the first fluid phase and the extraction fluid phase remain as substantially discrete layers. A means for communication between the first fluid and the extraction fluid is provided. The communication of the phases results in the extractive components being extracted from the first fluid into the extraction fluid. Agitation is stopped and the first fluid is recovered having reduced extractive components.

This is a division of application Ser. No 08/950,683 filed Oct. 15.1997, the entire disclosure of which is hereby incorporated byreference.

This application claims the benefit of the filing of U.S. ProvisionalPatent Application Serial No. 60/030,170, filed Oct. 31, 1996.

FIELD OF THE INVENTION

This invention pertains to segregated mixing and phase separationtechniques, in particular a method of extraction from multi-phasesystems, particularly two-phase systems wherein the phases are fluid,and/or slurry.

BACKGROUND OF THE INVENTION

Many processes require an extraction step in recovering the desiredproduct. In some extraction processes undesirable impurities may beremoved from a fluid system while in other extraction processes theproduct may be removed from the fluid system. Common extraction involvesplacing a fluid containing the component to be extracted (the extractivecomponent) in direct contact, usually by rapid mixing, with a secondfluid (the extraction fluid) which attracts or traps the extractivecomponent, thereby reducing the level of that component in the firstfluid. Unfortunately, extraction by conventional methods many timesleaves entrained phases of the extraction fluid in the fluid which isbeing acted upon. These entrained phases contain the very componentswhich are meant to be extracted from the first fluid. As an example,polymerization and hydrogenation of polymer cements requires the use ofpolymerization initiators and hydrogenation catalyst. Extraction of theinitiator and/or catalyst is required to produce a polymer relativelyfree of metals found in the initiator and/or catalyst. Conventionalmethods of extraction are to either disperse acids, such as sulfuric orphosphoric acid, into the polymer cement, or to disperse polymer cementinto acids, both methods commonly accomplished by rapid mixing for aperiod of time, followed by allowing the material to settle andseparate. Extraction by this conventional method leaves entrained acidphases in the polymer cement. Metal impurities successfully extracted tothe acid are thereby returned to and entrapped in the cement when theacid becomes entrained. Further, trapped acid phases reduce extractionefficiency and leave residuals of the acid, such as sulfates orphosphates, in the final polymer product.

Another problem with conventional extraction is that the rapid mixingcommonly leads to a “rag layer” upon settling. The rag layer is anemulsification of the first and second fluids that will not separate andhas no commercial use; it is a waste of an amount of the desired firstfluid. Therefore, it would be desirable to have an extraction technologythat achieves high extraction efficiency without leaving other residualsin the final product and which reduces or eliminates wasteful rag layer.

It has surprisingly been found that reduction of the level of mechanicalagitation during extraction allows for short-time extraction withsubstantially no residual contaminates or rag layers. In many instances,total extraction times are reduced from those of conventional methods.

SUMMARY OF THE INVENTION

One embodiment of the invention provides a process for extracting andseparating extractive components from fluids. A first fluid containingat least one extractive component and an extraction fluid are added to avessel, thereby creating a two-phase, two-layer system, wherein thefirst fluid and the extraction fluid are discrete and the two-phasesystem has a first fluid/extraction fluid interface. The two-phasesystem is then agitated wherein the first fluid phase and the extractionfluid phase remain as substantially discrete layers. A means forcommunication between the first fluid and the extraction fluid isprovided. The communication of the phases results in the extractivecomponent being extracted from the first fluid into the extractionfluid. Agitation is stopped and the first fluid is recovered havingreduced amounts of the extractive component.

Another embodiment provides a method for extracting and separatingimpurities from polymer cements. A polymer cement and an acid are addedto a vessel, thereby creating a two-phase, two-layer system, wherein thepolymer cement and the acid are discrete and the two-phase system has apolymer cement/acid interface. The two-phase system is then agitated ata rate that the polymer cement and the acid remain as substantiallydiscrete layers. A means for communication between the polymer cementand the acid is provided. Agitation is stopped and the polymer cement isrecovered having reduced impurities.

A third embodiment provides a method for extracting residues fromdeprotected polymer cements. Residues in deprotected cements arecommonly residuals of deprotection solutions, or hydrogenation catalyst,or both. A deprotected polymer cement and water are added to a vessel,thereby creating a two-phase, two-layer system, wherein the polymercement and the water are discrete and the two-phase system has a polymercement/water interface. The two-phase system is then agitated at a ratethat the deprotected cement and the water remain as substantiallydiscrete layers. A means for communication between the deprotectedcement and the water is provided. Agitation is stopped and thedeprotected cement is recovered having reduced residuals.

Another embodiment provides a process for mixing a fluid system whilemaintaining phase separation. A first fluid and a second fluid are addedto a vessel, thereby creating a two-phase, two-layer system, wherein thefirst fluid and the second fluid are discrete and the two-phase systemhas a first fluid/second fluid interface. The two-phase system is thenagitated at a rate that the first fluid phase and the second fluid phaseeach are well-mixed but remain as substantially discrete layers.

DETAILED DESCRIPTION OF THE INVENTION

The extraction method described works on any multi-phase fluid system.By fluid is meant fluid or slurry and a multi-phase system may consistof fluid, or slurry, or both. The viscosity of the fluid system merelychanges the contact and/or settling time but not the process of theinvention Therefore, the extraction process works for low viscosityfree-flowing liquors as well as high viscosity slurries as long as thefluid containing the impurities and the extraction fluid are ofdifferent densities and remain discrete phases when placed in contact.

To practice the extraction process, a first fluid having at least oneextractive component is contained in or is added to a vessel. Anextraction fluid is added to the vessel, creating a two-phase systemwherein the first fluid and the extraction fluid are discrete and thetwo-phase system has a first fluid/`extraction fluid interface. Thetwo-phase system is then agitated, or mixed, at a rate that ensures thefirst fluid phase and the extraction fluid phase remain substantiallydiscrete. This may be accomplished, for example by is lowering theagitating speed. Some communication must take place, however, betweenthe phases in order to allow the extraction fluid to contact trap andextract the extractive component. Communication is best accomplished byusing a vessel which contains a baffling system. Four longitudinallyoriented baffles placed radially at 90 degree intervals around the innercircumference of the vessel have been found to provide excellentcommunication between the phases.

It is desirable that each phase be well-mixed during the agitation step.This is accomplished, for example, by rotating at least one impeller ona shaft. A flat blade impeller has been found to provide excellentmixing results while keeping the phases substantially discrete. If morethan one impeller is used, the preferred positioning is to have a firstimpeller located in the first fluid and a second impeller located in theextraction fluid. When one impeller is used, or all impellers arelocated in the same phase, excellent results have been seen when atleast one impeller is located very near the first fluid/extraction fluidinterface.

Agitation or mixing is continued for a time to allow extractivecomponents in the first fluid to be extracted into the extraction fluid.The agitation is them stopped. It is preferred that the system beallowed to settle after agitation to allow any extraction fluid in thefirst fluid to separate from the first fluid. However, because the firstfluid and the extraction fluid are not dispersed into each other,settling time can be substantially reduced from conventional extractionmethods.

The process can be extended to include a second extraction stepfollowing the first thereby reducing extractive components in the firstfluid to an even lower level. The first batch of extraction fluid isremoved from the vessel and a second batch of extraction fluid is added.Once again a two-phase system is created wherein the first phase and theextraction phase are discrete and this second two-phase system has afirst fluid/extraction fluid interface. Agitation and settling isperformed substantially as described for the first extraction. It hasbeen seen that conducting the second extraction step at a loweragitation speed than the first extraction step helps reduce rag layers.

The process of the invention may be run as a batch or a continuousprocess. If a continuous process is used, the fluids would pass to asettling vessel to allow any entrained fluid to settle out.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

By way of example, the extraction method described has been found towork exceptionally well on polymer cements, particularly cements ofpolymerized conjugated dienes. These polymers may be mono-ols, diols orepoxidized polymers and have number average molecular weights betweenthe range of about 1,000 and 250,000 as measured by gel permeationchromatography. Solids contents of the polymers range from about 20% wtto about 50% wt, based upon the total weight of the cement. The polymercements may also be block copolymers of monovinyl aromatic andconjugated diene, such as ABA linear copolymers where A is a monovinylaromatic such as styrene and B is a conjugated diene.

Anionic polymerization of conjugated diene hydrocarbons with lithiuminitiators is well known as described in U.S. Pat. Nos. 4,039,503 andRe. 27,145, which descriptions are incorporated herein by reference.Polymerization commences with a monolithium, dilithium, or polylithiuminitiator which builds a living polymer at each lithium site.

Anionic polymerization is terminated by addition of a component whichremoves the lithium. For example, termination with water removes thelithium as lithium hydroxide and termination by addition of an alcoholremoves the lithium as a lithium alkoxide. The termination of livinganionic polymers to form functional end groups is described in U.S. Pat.4,417,029, 4,518,753 and 4,753,991 which are herein incorporated byreference.

Following termination, the polymers may be hydrogenated to reduceunsaturation of the polymerized conjugated diene, particularly when theconjugated diene is butadiene. Hydrogenation of at least 90%, preferablyat least 95%, of the unsaturation in butadiene polymers is achieved withnickel catalysts as described in U.S. Pats. Re. 27,145 and 4,970,254which are incorporated by reference herein.

The termination and hydrogenation steps result in release of fineparticles of lithium bases, nickel and aluminum which must be separatedfrom the polymer. The lithium bases may be separated before thehydrogenation step, or they may be separated with the nickel andaluminum after hydrogenation. Conventional methods of separation afterhydrogenation are to either disperse acids, such as sulfuric orphosphoric acid, into the polymer cement or to disperse the polymercement into acids. Both conventional processes involve rapid mixing fora period of time, followed by allowing the material to settle andseparate. Rapid mixing leads to a fully dispersed system of aqueous acidin the polymer cement and, even after settling times of 120 minutes orgreater, entrained acid phases remain in the polymer cement. It has beenfound that any nickel and/or lithium successfully extracted to the acidare returned to and entrapped in the cement by way of the entrainedacid. Therefore, the entrained acid reduces extraction efficiency andleaves residuals, such as sulfates or phosphates, in the final polymerproduct.

The process of the present invention drastically changes thisconventional separation, or wash step. After hydrogenation is complete,an aqueous acid solution is added to a vessel containing a polymercement, thereby creating a two-phase acid/polymer cement system. Theacid phase and cement phase are discrete at this point and a distinctacid-polymer cement interface is present. The two-phase system isagitated or mixed at a rate that is low enough to ensure that the acidand the polymer cement phases remain substantially discrete. Althoughconventional wisdom would indicate that lowering the rate of mixingwould result in intolerably long extraction times, it has been foundthat as long as some communication beyond the interface contact takesplace between the phases at this low speed, the acid will trap andextract lithium, nickel and aluminum. Communication may be accomplishedby using a vessel which contains a baffling system, such as severallongitudinally oriented baffles placed radially at intervals around theinner circumference of the vessel.

It is desirable that each phase remain well mixed during the agitationstep. This is accomplished by the use of any means which will keep thephases separated but individually well-mixed. As earlier described,mixing by rotating at least one impeller on a shaft can result in phaseswhich are well mixed but substantially separated.

Mixing continues for up to 30 minutes and then the agitation is stopped.It is preferred that the system be allowed to settle after agitation toallow the acid to separate from the polymer cement. For practicalpurposes, the settling is usually complete in less than 15 minutes,after which time no more appreciable amount of entrained fluid will beremoved.

For certain polymers high levels of lithium initiator or high levels ofhydrogenation catalyst may be used to produce the polymers. In thesecases, removal of the metals to an acceptable residual leveloccasionally requires a second wash step, substantially the same as thefirst wash. It has been found that further reducing the speed ofagitation of the second wash step, as compared to the speed of the firstwash step, reduces the occurrence of rag layer.

A conventional wash in which the acid and polymer cement phases arefully dispersed needs only about a minute of contact time to extract themetals but requires a settling time of 120 minutes or greater tosegregate out enough entrained acid and residuals to produce amarketable product. The process of the invention requires an average of30 minutes contact time but a settling time of only 15 minutes, afterwhich time very little entrained acid remains in the cement. Therefore,the total wash cycle of the invention is about 1¼ hours shorter induration than the conventional wash. Even if a second wash is required,a savings of about 30 minutes is seen. Such shortened process times canresult in significant savings during commercial production.

An additional advantage to the slow agitation process is the reductionor elimination of a rag layer. Conventional wash methods can result in acertain amount of polymer that forms an emulsion with the acid. Uponsettling, this highly stable emulsion settles between the cement layerand the acid layer and is called a “rag layer.” The acid will not settleout of the rag layer, and the acid is in too high a concentration forthe polymer in this layer to be of any use. Thus, reduction of the raglayer increases the product yield, another significant advantage forcommercial production.

By way of another example, the extraction method may be used to extractresiduals from a polymer deprotection step. When certain polymerizationinitiators are used, such as a protected functional initiator (PFI) asdescribed in U.S. Pat. Nos. 5,391,663 and 5,416,168, whose descriptionsare incorporated herein by reference, a chain end of the polymer maycontain residue of the lithium initiator. After polymerization andhydrogenation, this initiator residual at the front of the polymer chainmust be removed to generate the desired functional group. This step isoften referred to as deprotection. A variety of processes for removal ofthe protecting group are known; for a review, see T. W. Greene,“Protective Groups in Organic Synthesis,” J. Wiley and Sons, New York,1981. Deprotection preferably involves easily handled, relatively lowtoxicity, inexpensive reagents and mild, low cost process conditions.For example, deprotection of a low viscosity functionalized polymerwhich has been polymerized using a PHI such as described in U.S. Pat.No. 5,416,168 is accomplished by contacting the cement with a solutionof methanesulfonic acid, water, and an alcohol in the presence ofoxygen, oxidizing the catalyst and hydrolyzing the protecting group.After deprotection the cement contains methanesulfonic acid, which mustbe removed.

Using the process of the invention, water is added to a vesselcontaining the deprotected cement, thereby creating a two-phase system,wherein the deprotected cement and the water are discrete and thetwo-phase system has a deprotected cement/water interface. The system isthem agitated as already described herein such that the two phasesremain substantially discrete, and wherein some communication takesplace between the two phases. The acid is extracted from the deprotectedcement into the water. When agitation is stopped, a deprotected cementsubstantially free of acid is recovered.

In another embodiment of the invention, a method is provided for mixingphases of a multi-phase system while maintaining phase separation. Afirst and a second fluid are added to a vessel, thereby creating atwo-phase two-layer system wherein the first fluid and the second fluidare discrete and the two-phase system has a first fluid/second fluidinterface. The two-phase system is agitated at a rate wherein the firstfluid and the second fluid are each individually mixed but wherein thefirst fluid and the second fluid remain as substantially discretelayers.

EXAMPLES 1. Laboratory Studies

The extractions were conducted in a 1-gallon laboratory extraction unitwhich consisted of a jacketed glass vessel with a hot water bathconnected to the jacket. The level of liquid in the vessel was typicallymaintained so that the ratio of the depth of liquid to the insidediameter of the vessel was approximately 1:1. Two flat-blade 2-inchdiameter turbines, each containing six blades, were positioned in thevessel to provide agitation. Four baffles ¾-inch wide were placedradially at 90° inside the vessel. Nickel oxidation was accomplished bydelivering 3% mol oxygen/97% mol nitrogen via a ⅛-inch tube placed justbelow the lower flat blade turbine. The oxygen/nitrogen mix wasdelivered from a cylinder and metered with a rotameter.

The polymer cement contained hydrogenated ethylene butylene mono-olhaving molecular weight of about 3800 and with a primary hydroxylfunctionality at one end of the molecule, and hydrogenation catalyst.Cement was added to the vessel and agitated while heating to anextraction temperature of 60° C. (140° F.). 85% wt phosphoric acid wasdiluted directly with deionized water to the desired acid concentration.The acid was then heated to the extraction temperature and then added tothe cement, at the desired agitator speed for the extraction.Immediately after acid addition, 3% mol oxygen addition was delivered tothe extraction vessel at 5 SCFH for approximately 2 minutes. Thecement/acid mixture was agitated for 30 minutes. Agitation was thenshut-off and settling was allowed to occur for 1 hour. Final cement,aqueous, and rag phases, if present, were weighed. The amount ofentrained water in the cement was calculated and used as an indicationof the amount of entrained acid, as the acid concentration the entrainedaqueous phase is the same as that in the original aqueous phase.

The cement was analyzed for lithium, nickel and aluminum. Lithium wasanalyzed via ion chromatography. “Concentrated” aluminum and nickel (>10ppmw) were measured using Direct Current Plasma-Atomic Emission, while“dilute” nickel and aluminum (<10 ppmw) were measured using InductivelyCoupled Plasma-Atomic Emission. The percent weight polymer in thecements was determined by gravimetric analysis. Results are shown inTable 1.

TABLE 1 Results of Laboratory Extraction Studies Acid to EntrainedImpeller Cement Water After Lithium in Nickel in Rag Layer Solids ConcSpeed Acid Conc. Phase Ratio Separation^(a) Cement Cement (% wt of RunNo. (% wt) (rpm) (% wt) (v/v) (ppmw) (ppmw) (ppmw) cement) A. AcidConcentration and Phase Ratio Varied 2 13.3 1500 3 0.2 4400 7.5 5.2 2 313.3 1500 3 0.4 7300 9 3.6 1 4 13.3 1500 6 0.2 6900 18 7.2 3 5 13.3 15006 0.4 2700 9.1 3.5 8 B. Solids Concentration and Phase Ratio Varied 6 151500 3 0.2 4500 18 3.9 0 7 20 1500 3 0.2 4100 5.5 3.6 0 8 25.4 1500 30.2 5670 11 6.1 12 9 15 1500 3 0.4 12000 11 6.6 2.5 10 25.4 1500 3 0.423000 17 1.9 16 C. Impeller Speed Varied 11 20 900 3 0.2 4200 34 1.4 012 20 400 3 0.2 — 3.7 1 — 13-15 min 20 1000 3 0.2 6000 15 1 30 min 700010 1 45 min 6900 9 1 60 min 6600 13 1 0 14-15 min 20 1250 3 0.2 3600 30min 2600 45 min 1600 60 min 980 4.6 2 0 9 20 1500 3 0.2 4100 5.5 3.6 0D. Single Wash Extraction 14 20 1250 3 0.2 980 4.6 2 0 15 20 1250 3 0.211400 11.6 2 0 20 20 1250 3 0.2 6140 <1 <0.2 4 E. Double Wash Extraction22-1st Wash 20 1250 3 0.2 450 6 12 0 -2nd Wash 1250 2630 <1 <0.2 324-1st Wash 20 1250 3 0.2 1300 <1 0.4 0 -2nd Wash 1250 4600 <1 — 2.7 F.Reduction of Rag Layer After Second Wash 20-1st Wash 20 1250 3 0.2 61406 5 0 -2nd Wash 1250 0.1 5700 <1 <0.2 4 23-1st Wash 20 1250 3 0.2 13001.7 1.2 0 -2nd Wash 1250 4600 <1 <0.2 7.7 27-1st Wash 20 1250 4 0.2 27002.2 0.7 0 -2nd Wash 1250 3370 <2 — 3.8 35-1st Wash 20 1250 3 0.2 660 1.61.6 0 -2nd Wash 720 420 <1 <1 0 37-1st Wash 20 1250 3 0.2 4600 5.4 5.4 0-2nd Wash 720 1760 <1 <1 0 ^(a)Unless otherwise indicated, measurementis after 1 hour of separation time.

The process variables that are perceived to affect the extraction stepsignificantly are (i) temperature, (ii) acid concentration, (iii)acid-to-organic phase ratio, (iv) contact time, (v) settling time, (vi)impeller speed, and (vii) polymerization termination byproducts. Thedesired requirements for extraction in these studies were (i) removal ofnickel and lithium to 10 ppmw or less, (ii) mini on of entrained acid,and (iii) minimization of rag layer. It can be seen from the resultsshown in Table 1 that the efficiency of extraction of nickel and lithiumis directly tied to the percentage of acid entrained in the cement. Inthe first stage of extraction, virtually all the nickel and lithium weretransferred to the acid phase. The loss of extraction efficiencyoccurred when the acid phase remained entrained in the cement phase,thereby introducing nickel and lithium back into the cement.

The acid concentration and phase ratio were varied in Study A. Thehighest degree of rag formation occurred at an acid concentration of 6%and an acid-to-organic phase ratio of 0.4 (Run 5). At a phase ratio of0.2, no significant advantage was seen in using a higher acidconcentration (Runs 2 and 4). However, when the acid concentration washeld constant at 3% wt, an increased phase ratio resulted in about a 75%increase in entrained water (Runs 2 and 3).

The solids concentration and the phase ratio were varied in Study B. Theresults support the findings of Study A. At similar conditions, anincrease in phase ratio from 0.2 to 0.4 increased the entrained waterabout three times (Runs 6 and 9). Study B also revealed a sensitivity ofrag layer formation to solids level, all other conditions being constant(Runs 6, 7, and 8).

Impeller speed was varied in Study C. The acid concentration and phaseratio were maintained at 3% wt and 0.2 respectively. Samples wereremoved at 15, 30, 45 and 60 minutes of contacting time. It can be seenthat extraction is essentially complete at 15 minutes.

Studies D and E looked at the efficiency of one extraction step versustwo extraction steps. The results suggest that a second wash may benecessary to lower some residuals to the desired level. However, thesecond wash created a rag layer so Study F was conducted to look atreducing this rag layer. It can be seen that of the various variableswhich were altered, reduction of impeller speed had the greatest affect(Runs 35 and 37).

2. Field Studies

a. A mono-ol (ethylene butylene, approximately 3800 Mw, alcoholfunctionality) test run was carried out under similar conditions tothose previously described, only in a commercial size vessel with avolume phase ratio of 0.2 acid/cement, 30 minute extraction time, 60° C.(140° F.) extraction temperature, and various settling times. The acidconcentration was 3.5% wt. The acid and cement phases were contactedduring two washes, both at an impeller speed of 35 rpm, to give a tipspeed of 550 ft/min. Under these mixing conditions, samples were takenfrom the commercial size vessel from the bulk cement and the acidphases. These samples observed less than 1% acid in the cement phase byvolume, and less than 1% cement in the acid phase by volume, suggestingthat the extractions occurred with extreme stratification in thecommercial vessel. The extraction results are shown in Tables 2 and 3.

TABLE 2 Field Extraction Studies - Mono-ol Contact Settling Nickel inLithium Entrained Phosphate Wash Time Time Cement in Cement Water inCement^(a) Batch # Step (min) (min) (ppmw) (ppmw) (ppmw) (ppmw) 1 First30 120 0.3 0.81 458 — Second 30 140 0.3 0.36 398 12.3 2 First 30 1200.51 2.1 642 — Second 30 140 0.31 0.6 706 30 3 First 30 120 1.05 0.652030 — Second 30 140 0.21 1.92 1923 91 4 First 30 120 0.24 1.72 646 —Second 30 140 0.18 0.45 428 22 5 First 30 60 0.68 9.5 1521 — Second 3060 0.08 0.92 869 31.4 6 First 30 60 0.6 5 — — Second 30 40 0.7 — 196 — 7First 30 60 — 1 622 — Second 30 60 0.11 — 1390 36.2 8 First 30 60 0.13 1683 — Second 30 60 5.3 1.9 408 65 9 First 30 60 0.67 5 — — Second 30 600.12 1 — 19 10 First 30 60 0.4 3 — — Second 30 60 0.2 1 865 19 11 First30 60 0.45 3 — — Second 30 60 0.12 1.2 658 28 ^(a)Phosphoric acidresidue

TABLE 3 Batch Extraction and Settling Field Studies - Mono-ol Li inCement Ni in Cement Entrained Water Time (ppmw) (ppmw) (ppmw) (min) 1stWash 2nd Wash 1st Wash 2nd Wash 1st Wash 2nd Wash Acid/Cement ContactTime  0 363 <1 63 <0.2  5 198 1.5 26 0.4 10 259 2.8 20 0.4 20 1.4 3.6<0.2 0.3 30 <1 3.4 <0.2 0.3 Settling Time 15 96 136 30 107 104 60 127105 90 149 32 120  71 98

Results of commercial scale test on a mono-ol revealed that a contacttime of 30 minutes was highly efficient in removing Li and Ni.Extraction was found to be essentially complete at a time between 10 and20 minutes, so the time may actually be reduced by at least 10 minutes.Further, the settling was essentially completed within the first 15minutes, as evidenced by the lack of change in entrained water in thecement over time. Therefore, settling time may also be reduced, makingan extraction cycle time of less than 45 minutes possible.

b. A diol (ethylene butylene, approximately 3200 Mw, diol functionality)test run was carried out, where extraction of methanesulfonic acid wasaccomplished with the previously described approach of keeping thecement and wash phase segregated. A commercial size vessel was used witha cement to water phase ratio of 0.1, a 15 minute extraction time, 60°C. (140° C.) extraction temperature, and various settling times. Thewater and cement phases were contacted at an impeller speed of 30 rpm,to give a tip speed of 420 ft/min. Under these mixing conditions,samples were taken from the bulk cement and the aqueous phases. Thesesamples observed less than 1% aqueous phase in the cement by volume, andthan 1% cement phase in the aqueous phase by volume, suggesting that theextractions occurred with extreme stratification in the commercialvessel. The extraction results showed that the methanesulfonic acidconcentration in the aqueous acid phase was 9.7% wt methanesulfonic acidafter 15 minutes of extraction; a value of approximately 10% wt wasexpected for complete extraction. Hence the extraction ofmethanesulfonic acid from the cement was essentially complete after 15minutes. The water and methanesulfonic acid concentration profile duringsettling is summarized in Table 4.

TABLE 4 Field Extraction Studies - Diol Settling Time After MSA inCement Water in Cement Extraction (min) (% w) (% w) 20 0.30 3.9 25 0.201.8 50 0.18 1.5 80 0.12 1.1 120  0.11 1.0

The results suggest that settling was essentially complete after 80minutes. No rag layer was observed when decanting the aqueous wash phasefrom the cement.

c. A test run was carried out where a mono-ol was made as a precursorfor epoxidation. The molecule was an isoprene-butadiene block co-polymerwith a molecular weight of approximately 6000. The primary goal of thisextraction was to remove lithium, as nickel and aluminum levels weresignificantly lower than in previous examples. The commercial vesselpreviously described for the mono-ol run was used with a volume phaseratio of 0.2 acid/cement, 30 minute extraction time, 60° C. (140° F.)extraction temperature, and various settling times. The acidconcentration was 3.5% wt. The acid and cement phases were contactedduring one wash at an impeller speed of 35 rpm, to give a tip speed of550 ft/s. Under these mixing conditions, samples were taken from thecommercial size vessel from the bulk cement and acid phases. Thesesamples observed less than 1% acid in the cement phase by volume, andless than 1% cement in the acid phase by volume, suggesting that theextractions occurred with extreme stratification in the commercialvessel. Results showed that the lithium concentration in the cementdropped from 210 ppm at the beginning of the extraction to 26 ppm fiveminutes into extraction. The concentration dropped to 8 ppm after 15minutes and 6 ppm after 30 minutes, suggesting the extraction wasessentially complete after 15 minutes. After 30 minutes of extractiontime the impeller was turned-off The lithium concentration in the cementwas 500 ppb after 2 minutes of settling, 4 ppm after 20 minutes, and 3ppm after 60 minutes. These results suggest the additional settling timebeyond 2 minutes was not beneficial.

3. Impeller Speed

A laboratory scale mixing experiment was carried out to bettercharacterize the contacting pattern of the acid and cement over a rangeof mixing conditions. A hydrogenated cement was contacted with 3% wtphosphoric acid at a phase ratio of 0.2 and a temperature of 60° C.(140° F. An initial impeller speed of 300 rpm was used, and the impellerspeed was then increased. At 300 rpm there was virtually no intimatecontacting between the acid and cement. At 400 rpm intimate contactingof the two phases was observed in a small zone (herein referred to asthe contacting zone) between discrete acid and cement phases. At 600 rpmsmall acid droplets were visible in the cement, and the contacting zonegrew. At 710 and 900 rpm the contacting zone continued to grow, althoughdistinct acid and cement phases were still clearly present with somedispersion of small droplets in each. Finally, at 1100 rpm, or a tipspeed of 570 ft/min, the stratification disappeared and the acidappeared to be completely dispersed into the cement from a macroscopicviewpoint. The results are shown in Table 5.

TABLE 5 Mixing Experiment Impeller Power Per Speed Tip Speed Volume(rpm) (ft/min) (hp/gallon) Comments  300 157 0.0003 Completesegregation; no dispersion of phases  35^(a) 550 0.0008 Acid and cementphases discrete; acid intermingled with cement  550 290 0.002  700 3700.004 Acid and cement phases discrete; contact zone apparent; aciddispersed in cement  900 470 0.0081 Acid and cement phases discrete;contact zone apparent; acid intermingled with cement 1100 575 0.015 Twophases well-mixed macroscopically ^(a)From commercial scale test

The results of the mixing experiment show that two phase stratificationoccurs in the different sized vessels at different tip speeds.Consequently, a more accurate scale-up criteria may be power input perunit volume.

While this invention has been described in detail for the purpose ofillustration, it is not to be construed as limited thereby but isintended to cover all changes and modifications within the spirit andscope thereof.

We claim:
 1. A method for extracting and separating extractivecomponents from a multi-phase fluid system, said method comprising:passing a first fluid having at least one extractive component to avessel; passing an extraction fluid to said vessel, thereby creating atwo-phase two-layer system wherein the first fluid and the extractionfluid are discrete and the two-phase system has a first fluid/extractionfluid interface; agitating the two-phase system at a rate wherein thefirst fluid phase and the extraction fluid phase remain as substantiallydiscrete layers; contacting said first fluid and said extraction fluidbeyond the interface without dispersing said first fluid in saidextraction fluid; extracting said at least one extractive component fromthe first fluid into the extraction fluid; stopping agitation; andrecovering the first fluid having reduced extractive components.
 2. Themethod according to claim 1 wherein agitation is accomplished by therotation of at least one impeller.
 3. The method according to claim 2wherein at least one impeller is located in the first fluid phase and atleast one impeller is located in the extraction fluid phase.
 4. Themethod according to claim 1 further comprising separating extractionfluid dispersed in said first fluid from said first fluid by allowingthe two-phase system to settle after agitation.
 5. The method accordingto claim 1 wherein no rag layer is formed.
 6. A method for extractingand separating impurities from polymer cements, said method comprising:adding a polymer cement to a vessel; adding an extraction fluid to thevessel, thereby creating a two-phase two-layer extraction fluid/polymercement system wherein the extraction fluid phase and the polymer cementphase are discrete and the two-phase system has an extractionfluid/polymer cement interface; agitating the two-phase system, whereinthe extraction fluid and the polymer cement phases remain assubstantially discrete layers; contacting the polymer cement and theextraction fluid beyond the interface without dispersing the polymercement in the extraction fluid; extracting impurities from the polymercement into the extraction fluid; stopping agitation; and recovering apolymer cement with reduced impurities.
 7. The method according to claim6 wherein agitation is accomplished by the rotation of at least oneimpeller.
 8. The method according to claim 7 wherein at least oneimpeller is located in the polymer cement phase and at least oneimpeller is located in the extraction fluid phase.
 9. The methodaccording to claim 7 fiber comprising separating said extraction fluiddispersed in said polymer cement from said polymer cement by allowingthe two phase system to settle after agitation.
 10. The method accordingto claim 9 wherein the extraction fluid is an acid.
 11. The methodaccording to claim 10 wherein a phase ratio of volume of the acid tovolume of the cement is less than about 0.5.
 12. The method according toclaim 11 wherein the phase ratio is about 0.2.
 13. The method accordingto claim 6 wherein no rag layer is formed.
 14. A method for extractingimpurities from a deprotected polymer cement, said method comprising:adding a deprotected polymer cement to a vessel, said deprotectedpolymer cement containing residues; adding water to said vessel, therebycreating a two-phase two-layer system wherein the deprotected polymercement and the water are discrete and the two-phase system has adeprotected polymer cement/water interface; agitating the two-phasesystem, wherein the deprotected cement and the water remain assubstantially discrete layers; contacting said deprotected polymercement and said water beyond the interface without dispersing saiddeprotected cement in said water; extracting said residues from thedeprotection cement into the water; stopping agitation; and recoveringthe deprotected polymer cement substantially free of said residues. 15.A method for mixing phases of a multi-phase system while maintainingphase separation, said method comprising: adding a first fluid to avessel; adding a second fluid to said vessel, thereby creating atwo-phase two-layer system wherein the first fluid and the second fluidare discrete and the two-phase system has a first fluid/second fluidinterface; and agitating the two-phase system, wherein the first fluidand the second fluid are each individually mixed, and wherein the firstfluid and the second fluid remain as substantially discrete layers. 16.A method according to claim 15 wherein agitation is accomplished by therotation of at least one impeller.
 17. A method according to claim 16wherein at least one impeller is located in the first fluid and at leastone impeller is located in the second fluid.